Allow `#`-private names in parameter property positions

Search Terms

hard privacy https://github.com/microsoft/TypeScript/issues/31670

Suggestion

allow create hard privacy like we do private in constructor(private foo: number)

Use Cases

Examples

allow use constructor(#foo: number) {} or constructor(private #foo: number) {} or constructor(hard private #foo: number) {}

for same as

#foo: number;
constructor(foo: number) {
		// This works.
		this.#foo = foo;
	}

class C {
	constructor(#foo: number) {}

	log() {
		console.dir(this.#foo);
		return this
	}
}

let o = new C(777).log();

// error
o.#foo;

same as

class C {
	#foo: number;

	constructor(foo: number) {
		// This works.
		this.#foo = foo;
	}

	log() {
		console.dir(this.#foo);
		return this
	}
}

let o = new C(777).log();

// error
o.#foo;

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

No se nombran archivos, pruebas ni puntos de entrada. Empieza revisando las formas solicitadas de los parámetros del constructor y los ejemplos de clases que las acompañan; se considera terminado cuando se admite la sintaxis propuesta de propiedad de parámetro #foo y se conserva el comportamiento de acceso privado mostrado.